Villion M, Szatmari G
Dèpartement de Microbiologie et Immunologie, Université de Montréal, Que., Canada.
FEMS Microbiol Lett. 1998 Jul 1;164(1):83-90. doi: 10.1111/j.1574-6968.1998.tb13071.x.
The Xer site-specific recombination system is involved in the stable maintenance of replicons (certain plasmids and chromosomes) in Escherichia coli and other bacteria by converting multimers into monomers. This system requires a cis-acting DNA sequence (the chromosomal dif site or the ColE1 cer site) and two trans-acting factors: the XerC and XerD recombinases, which belong to the lambda integrase family of tyrosine site-specific recombinases. In addition, in order to resolve plasmid multimers into monomers, two additional factors are required: the ArgR and PepA proteins. We have previously shown the presence of xerC and xerD genes (and their function) by Southern hybridisation and by in vivo recombination in a wide variety of Enterobacteriaceac. We have now cloned and sequenced the xerD gene of Proteus mirabilis using degenerate and inverse PCR methods. This gene encodes a tyrosine recombinase which is highly similar to the E. coli XerD recombinase, is capable of complementing an E. coli xerD mutant, and displays sequence-specific DNA binding activity.
Xer位点特异性重组系统通过将多聚体转化为单体，参与大肠杆菌和其他细菌中复制子（某些质粒和染色体）的稳定维持。该系统需要一个顺式作用DNA序列（染色体dif位点或ColE1 cer位点）和两个反式作用因子：XerC和XerD重组酶，它们属于酪氨酸位点特异性重组酶的λ整合酶家族。此外，为了将质粒多聚体分解为单体，还需要另外两个因子：ArgR和PepA蛋白。我们之前通过Southern杂交和在多种肠杆菌科细菌中的体内重组，证明了xerC和xerD基因的存在（及其功能）。我们现在使用简并PCR和反向PCR方法克隆并测序了奇异变形杆菌的xerD基因。该基因编码一种酪氨酸重组酶，与大肠杆菌XerD重组酶高度相似，能够互补大肠杆菌xerD突变体，并表现出序列特异性DNA结合活性。
